Minoxidil

Minoxidil is a vasodilator medication known primarily for its ability to slow hair loss and promote hair regrowth. It is available over-the-counter for the treatment of androgenetic alopecia (male-pattern baldness) and is also used to treat high blood pressure.

Mechanism of Action:

The exact mechanism by which minoxidil promotes hair growth is not fully understood. However, several theories exist, including:

• Vasodilation: Minoxidil is a potassium channel opener, causing vasodilation (widening of blood vessels). This increased blood flow to hair follicles may stimulate growth.
• Stimulation of Hair Follicles: It is believed to directly stimulate hair follicles, prolonging the anagen (growth) phase and shrinking the telogen (resting) phase.
• Increased DNA Synthesis: Some research suggests that minoxidil may increase DNA synthesis in follicular cells.

Indications:

• Androgenetic Alopecia: The primary indication for topical minoxidil is the treatment of androgenetic alopecia in both men and women.
• Hypertension: Oral minoxidil is used as an antihypertensive medication, typically reserved for severe or resistant hypertension due to its potential side effects.

Administration:

• Topical Minoxidil: Typically applied twice daily to the scalp in a liquid or foam formulation. Different strengths are available (e.g., 2% and 5%).
• Oral Minoxidil: Administered orally for hypertension, typically in tablet form. Dosage varies depending on the individual's blood pressure.

Side Effects:

• Topical Minoxidil: Common side effects include scalp irritation, itching, dryness, and initial shedding of hair. Less common side effects include unwanted hair growth on other parts of the body (hypertrichosis), and rarely, systemic absorption causing dizziness or lightheadedness.
• Oral Minoxidil: Side effects of oral minoxidil can be more significant and include fluid retention, tachycardia (rapid heart rate), and hypertrichosis. It also carries a risk of pericardial effusion (fluid around the heart).

Contraindications:

• Topical Minoxidil: Contraindications are relatively few but may include sensitivity to the drug or its excipients.
• Oral Minoxidil: Contraindications include pheochromocytoma and hypersensitivity to minoxidil. Caution is advised in patients with pre-existing cardiovascular conditions.

Drug Interactions:

Oral minoxidil can interact with other antihypertensive medications, potentially leading to excessive lowering of blood pressure.

Pregnancy and Lactation:

The safety of minoxidil during pregnancy and lactation has not been fully established. It should be used with caution and only if the potential benefits outweigh the risks.